Selection valve with ferrule cluster

ABSTRACT

A multi-port injection/selection valve utilizes a ferrule cluster to connect tubes or capillaries to a common port in the valve. The use of micro ferrule clusters, as opposed to conventional connectors such as nuts and/or bolts, permits the capillary ends to be positioned in extremely close proximity to the valve rotor and to each other, thus minimizing the volume between two capillaries when they are in brought into fluid communication with each other.

FIELD OF THE INVENTION

[0001] This invention relates to a multi-port valve that is used forselection of fluid streams and/or injection of fluids in processes suchas liquid chromatography. In particular, the invention relates to aninjection/selection valve that utilizes a ferrule cluster to connecttubes or capillaries to a common port in the valve.

BACKGROUND OF THE INVENTION

[0002] Multiport selector/injector valves are well known and have beenused in a variety of industrial processes, such as liquidchromatography. For example, selection valves are commonly used inliquid chromatography and other analytical methods to direct fluid flowalong alternate paths. Such valves are also used to terminate fluidwithdrawal from one source and select another source of fluid, forexample, such as when a variety of streams in an industrial process isselectively sampled for analysis.

[0003] Injector/selector valves are often used in high pressure liquidchromatography (HPLC) or gas chromatography (GC). U.S. Pat. No.4,242,909 (Gundelfinger '909), which is hereby fully incorporated byreference, describes a sample injection apparatus for withdrawing liquidsamples from vials and injecting them into a chromatographic column orother analyzing device. The apparatus is said to minimize wastage, crosscontamination, and dilution of the samples, and to be capable ofautomation with a minimum of complexity. Injector/selector valves areparticularly useful in chromatographic applications since a substantialamount of time and effort is required to set up a particular HPLC or GCsystem, which may often utilize multiple columns and/or multipledetection systems. Multiport selection valves permit the operator of thechromatograph to redirect flows such that particular samples areselected for injection into a particular column, or alternatively, todirect the output from a particular column to one or more differentdetectors.

[0004] As mentioned above, multiport selection valves have been knownfor some time, including those which utilize a cylindrical rotor andstator combination. In some of these valves, the stator holds the fluidtubes in fixed relation to each other and presents the tube ends to arotor face which may contain a grooved surface. By varying the angle ofthe rotor, the tubes are selectively brought into fluid communication.One type of injector/selector valve using a rotor/stator combination isthe Type 50 rotary valve from Rheodyne, Incorporated. The Type 50 valvesare said to operate by rotation of a flat rotor against a flat stator(see “Operating Instructions for Type 50 Teflon Rotary Valves,”Rheodyne, Incorporated, printed in U.S.A. 4/94). Another rotor/statorselector valve is shown in U.S. Pat. No. 5,193,581 (Shiroto, et al.).The valve is said to comprise, among other things, a stator plate havinga plurality of outlet holes extending through the stator plate andarranged in a circle concentric with a valve casing, and a rotor havinga U-shaped passage formed in the rotor. The rotor is said to be rotatedthrough a desired angle so that an inlet hole can be in fluidcommunication with selected ones of the outlet holes through theU-shaped passage of the rotor.

[0005] U.S. Pat. No. 5,419,419 (Macpherson) describes a rotary selectorvalve that is used in connection with an automatic transmission in anautomobile. A motor is said to index a shear plate of the selector valveto predetermined positions for shifting the transmission. A series ofworking lines as shown in FIG. 6 are maintained in a closed spatialrelationship with the casing.

[0006] U.S. Pat. No. 3,494,175 (Cusick, et al.) discloses a valve havinga plurality of capillaries which are held in spaced relationship withina manifold plate member. U.S. Pat. No. 3,752,167 (Makabe) discloses afluid switching device including a plurality of capillaries that areheld within threaded holes by couplings. A rotary member allows fluidcommunication between the tubes. U.S. Pat. No. 3,868,970 (Ayers, et al.)discloses a multipositional selector valve said to be adapted with ameans for attaching a plurality of chromatographic columns to the valve,such that the flow can be directed into any of the columns. U.S. Pat.No. 4,705,627 (Miwa, et al.) discloses a rotary valve said to consist oftwo stator discs and a rotor disposed between the two stator discs. Eachtime the rotor is turned intermittently it is said, different passagesare formed through which the fluid in the valve runs. U.S. Pat. No.4,722,830 (Urie, et al.) discloses multiport valves. The multiportvalves are said to be used in extracting fluid samples from sample loopsconnected with various process streams.

[0007] In many applications using selector/injector valves to directfluid flows, and in particular in liquid and gas chromatography, thevolume of fluids is small. This is particularly true when liquid or gaschromatography is being used as an analytical method as opposed to apreparative method. Such methods often use capillary columns and aregenerally referred to as capillary chromatography. In capillarychromatography, both gas phase and liquid phase, it is often desired tominimize the internal volume of the selector or injector valve. Onereason for this is that a valve having a large volume will contain arelatively large volume of liquid, and when a sample is injected intothe valve the sample will be diluted, decreasing the resolution andsensitivity of the analytical method.

[0008] In the design of selector or injector valves with minimalinternal volume, the prime design consideration is to bring all of thefluid passages into the closest possible proximity to each other. To dothis with conventional capillary connectors is very difficult, since thenuts of the connectors are relatively large and require a fair amount ofspace. Thus, the valve itself has to be relatively large in order toaccommodate the connections.

[0009] One solution to the large connectors has been to drill theinjector ports on an angle. By angling the injector ports, the ends ofthe channels can all emerge in close proximity to a common point, whilethe opposite ends of the channels are sufficiently spaced apart toaccommodate the larger connectors. An example of this approach is shownin U.S. Pat. No. 5,419,208 (Schick), which is hereby fully incorporatedby reference. However, this approach has certain drawbacks. First,angled holes are difficult to produce and expensive to machine. Further,the angled passage from the capillary connector to the center of thevalve stator is longer than it would be if the capillary could beconnected directly on the face of the valve in close proximity to othercapillaries. This additional length creates additional dead volume,which is undesirable as noted above. A further disadvantage of thisapproach is that the emerging hole near the center of the valve statorhas an elliptical shape, which is not desirable.

[0010] Another type of capillary connection is shown in U.S. Pat. No.4,792,396 (Gundelfinger '396), which is hereby fully incorporated byreference. Gundelfinger '396 describes a frame used as part of aninjector said to be useful in loading a sample at high pressure into achromatographic column. The frame is said to comprise ferrules forsealing tubes, and it is said that a tube coupling hole in the frame cancouple to a standard {fraction (1/16)}″ tube, but also can couple to amuch smaller diameter tube useful for minimizing dispersion when smallsamples or small chromatographic columns are used. The use of ferrulesto make capillary or tubing connections to chromatography apparatus isalso shown in, for example, U.S. Pat. Nos. 5,674,388 (Anahara),5,744,100 (Krstanovic), 5,472,598 (Schick), 5,482,628 (Schick), and5,366,620 (Schick).

[0011] It would be desirable to have a selector/injector valve that canbe made with the smallest possible valve volume. There is also a needfor an injector/ selector valve which brings capillary or tube ends intothe closest possible proximity to each other and to the valve stator sothat valve dead volume is minimized. Finally, there is also a need for acapillary connector system that can be used to connect capillaries inthe closest possible proximity.

SUMMARY OF THE INVENTION

[0012] The invention relates to a multi-port injection/selection valvethat utilizes one or more ferrule clusters to connect tubes orcapillaries to a common port in the valve. The ferrule clusters connectthe tubes or capillaries to the body of the valve assembly. The use offerrule clusters, as opposed to conventional connectors such as nutsand/or bolts, permits the capillary ends to be positioned in extremelyclose proximity to the valve rotor and to each other, thus minimizingthe space between two capillaries when they are in brought into fluidcommunication with each other (i.e., the “dead volume” in theconnection). The ferrule clusters can be made extremely small.

[0013] In one embodiment the invention is a valve, comprising: a) aplurality of ferrules formed into one or more ferrule clusters, each ofsaid ferrules having a ferrule through-hole; b) a stator in contact withat least one of said ferrule clusters, said stator having a stator frontside and a stator flat surface opposite said front side, said statorfront side having a plurality of impressions into which some or all ofsaid ferrules are received, each of said impressions opening to aterminal cylindrical bore (tube pocket), each of said impressions alsohaving a stator through-hole opening onto said stator flat surface; c) aplurality of capillary tubes, each of said capillary tubes extendingthrough at least one of said ferrule through-holes and into a statorimpression up to the terminus of said cylindrical bore; d) means forapplying pressure to said one or more ferrule clusters; and e) a rotorcomprising a stator-contact surface and a fluid communication channel,said stator-contact surface abutting said stator flat surface and beingrotatable about an axis to establish fluid communication betweenselected pairs of capillaries through said fluid communication channel.

[0014] In yet other embodiments, the invention is a capillarychromatographic system comprising the valve of the invention. In stillother embodiments the invention is a method for carrying out achromatographic analysis and a method for connecting capillary tubes toa chromatographic system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a sectional view showing a valve according to oneembodiment of the invention.

[0016]FIG. 2 shows a front view and a sectional view along line AA ofone type of ferrule cluster useful in the present invention.

[0017]FIGS. 3A and 3B show sectional views of two types of ferruleclusters of the invention positioned within a valve of the invention.

[0018]FIG. 4 shows one embodiment of the ferrule backup plate of theinventive valve.

[0019]FIG. 5 shows the ferrule-contact surface of one type of statoruseful in the inventive valve, as well as a sectional view of the samestator.

[0020]FIG. 5A shows an enlarged sectional view of a portion of thestator shown in FIG. 5.

[0021]FIG. 6 and FIG. 7 show the stator-contact surface of two differentembodiments of the valve rotor, as well as a sectional views of saidrotor embodiments.

[0022]FIG. 8 shows a sectional view of another valve of the invention.

DETAILED DESCRIPTION

[0023] As seen in FIG. 1, one embodiment of the inventive valvecomprises a plurality of ferrules formed into two ferrule clusters 10Aand 10B. As best shown in FIG. 2, in one embodiment the ferruleclusters, exemplified by 10A, comprise a plurality of ferrules 10 a-10 gwhich are integrally formed into a one-piece ferrule cluster as shown inFIG. 2 or FIG. 3A. The ferrules of the invention may be of thesingle-ended type, as shown in FIGS. 1 and 2, or the double-ended type,as best shown in FIG. 3A. The double-ended type approximates twosingle-ended ferrules with their ends joined. Thus, the double-endedferrule has tapered gripping portions on both of its ends.

[0024] Referring again to FIG. 2, the ferrules are positioned such thatthere is a single ferrule 10 g located at the center of a circle 10 j.The remaining ferrules 10 a-10 f are distributed around thecircumference of circle 10 j and are centered on said circumference. Theferrules shown in FIG. 2 are of the single-ended type, having a grippingend exemplified by 10 h and a compression end exemplified by 10 i. Thedouble-ended ferrules shown in FIG. 3A have only two gripping ends.Referring to FIG. 2, the gripping ends of both the single-ended anddouble-ended ferrules are exemplified by gripping end 10 h, which ischaracterized by a tip diameter d (gripping end tip diameter) as shownin FIG. 2. The single-ended and double-ended ferrules are bothcharacterized also by exterior cone angle θ. When pressure is applied tothe compression end of the single-ended ferrule, or to either grippingend of a double-ended ferrule, the gripping ends are all forced intoimpressions on the valve stator, or into conical portions of the ferrulethrough-holes (as in the case of stacked ferrule clusters as discussedbelow), and/or into impressions on the ferrule cluster back-up plate (inthe case of the double-ended ferrules, as shown below). This causes theferrule gripping end tip diameters to be reduced, in turn causing theferrule gripping ends to “bite” into and hold the capillaries which aredisposed in the respective through-holes of the ferrules.

[0025] Referring to FIG. 2, each single-ended ferrule has athrough-hole, exemplified by through-hole 11, into which a capillary(capillary tube) or other tube is received. The terms “capillary” or“capillary tube” shall be used interchangeably herein, and shall beunderstood to refer to a tube having and outside diameter of from about50 to about 1600 microns. In one embodiment of the invention, theferrule through-holes are as shown in FIG. 2 and comprise a cylindricalportion 11 a and first and second conical portions 11 b, and 11 c,respectively. The diameter of cylindrical portion 11 a can be sized asneeded to accommodate tubes of any diameter. In some embodiments of theinvention, the through-hole cylindrical portion 11 a has a diameter offrom about 0.30 millimeters (mm) to about 0.45 mm, alternatively fromabout 0.35 mm to about 0.41 mm, and in yet another alternative fromabout 0.38 mm to about 0.41 mm. The conical sections of thethrough-holes each have a wide end and a narrow end, as shown in FIG. 2.The cylindrical portion of through-hole 11 extends along length L of thegripping end 10 h. The first and second conical sections 11 b and 11 care characterized by interior cone angles α and β. The value of α, θ,and L are not particularly critical, but β is normally about 30 to 45degrees. In any case, the value of β is adjusted so that a gripping endof another ferrule can be received in second conical section 11 c whenthe ferrule clusters are stacked, as discussed below. The secondthrough-hole conical section 11 c is also characterized by the diameterof its narrow end, d2 (narrow end diameter). This is shown forconvenience on through-hole 11A. Naturally, the through-hole diameter ofthe ferrules can be measured at any point along the length of thethrough-hole, and in the case of the single-ended ferrules shown in FIG.2 the diameter will vary in the first and second conical portions 11 band 11 c, depending on where along the through-hole the measurement ismade. As for the double-ended ferrule through-holes, the through-holediameter may vary, but the through-holes preferably have a uniformdiameter along the length of the through-hole. In one embodiment of theinventive valve, the ferrule through-holes have a maximum diameter atany point along the through-hole of from about 0.35 mm to about 0.90 mm,or from about 0.45 mm to about 0.80 mm, or from about 0.55 mm to about0.70 mm, alternatively from about 0.65 mm to about 0.70 mm. While theferrules shown in FIG. 2, FIG. 3A, and FIG. 3B have a specific shape,the ferrules useful in the inventive valve may have any number ofexterior shapes and/or through-hole geometries, as long as the ferrulesperform the usual function of a ferrule, namely gripping the capillaryor tube inserted through the ferrule when compressive forces are appliedto the ferrule.

[0026] The inventive valve comprises one double-ended ferrule cluster orone or more single-ended ferrule clusters. When two or more single-endedferrule clusters are employed, they are preferably arranged in a“stacked” configuration. Referring again to FIG. 1, the two ferruleclusters 10A and 10B are shown in a stacked arrangement. The detail ofthis arrangement is best shown in FIG. 3B. In the stacked ferrulecluster arrangement using two ferrule clusters, a second cluster 10B ispositioned behind a first cluster 10A. The capillaries 13 extend throughthe ferrule through-holes in both clusters, and the ferrule grippingends exemplified by 10 h of second cluster 10B are received andcompressed in the second conical sections, exemplified by 11 c, of theferrules in ferrule cluster 10A. Thus, each of the capillaries 13 isgripped by two ferrule gripping ends. Naturally, three or more clustersmay be stacked in the fashion shown in FIG. 3B.

[0027] Referring again to FIG. 1, a ferrule back-up plate 12, best shownin FIG. 4, holds the stacked ferrule clusters 10A and 10B in place andtransmits compressive forces to the ferrules so that they grip thecapillaries 13 inserted through them. Referring to FIG. 4, the back-upplate is supplied with through-holes 12 a-12 g, corresponding to ferrulethrough-holes 10 a-10 g on ferrule clusters 10A and 10B. Through-holes12 a-12 g are positioned so that the capillary tubes may pass throughthem in order to be received in the ferrule through-hole openings.Referring to FIG. 3B, the backup plate 12 is placed against the flatside 10 s of the ferrule cluster 10B and is adapted to transmitcompressive forces to the ferrule clusters so that the ferrules arecompressed and thus grip the individual capillary tubes placed in eachferrule. In one embodiment of the invention, the compressive force issupplied through the ferrule compression plate 14 shown in FIGS. 1 and3. The compression plate 14 is bolted to a base plate 16 and contactsthe ferrule back-up plate 12 thus urging the back-up plate against theferrule cluster as the bolts are tightened. The base plate in turn issecured to a bearing assembly housing 18. However, it should be clearthat any means for applying pressure to the ferrules and ferrule clustermay be employed. Such means may, for example, utilize pressure suppliedby hydrostatic (including any pressurized liquid), electromagnetic, orpneumatic sources, in addition to pressure supplied by the tightening ofthreaded connections and the like as exemplified in FIG. 1.

[0028] Referring again to FIG 1., a valve stator 20 is held in place bya stator hold down plate 22 and receives the capillaries 13. As bestshown in FIG. 5, the valve stator 20 has a stator front side 20 scomprising a plurality of conical impressions 20 a-20 g for receivingthe ferrules of ferrule cluster 10A. Each conical impression opens to aterminal cylindrical bore, alternatively referred to herein as a “tubepocket,” exemplified by 20 i. Each conical impression also has athrough-hole, exemplified by 20 h, which opens onto the flat statorsurface 24.

[0029]FIG. 5A shows an enlarged sectional view of conical impression 20a, which is exemplary of the other conical impressions. As shown in FIG.5A, conical impression 20 a opens to a tube pocket 20 i, the tube pocket20 i having a terminus coincident with surface 20 j. Through-hole 20 hextends from surface 20 j and opens onto stator flat surface 24. Innormal use, a capillary tube (not shown in FIG. 5A) would extend throughone or more ferrule through-holes (also not shown), then through conicalimpression 20 a and into tube pocket 20 i up to stator through-hole 20 hso that the end of the capillary is substantially flush with theterminus of the tube pocket at surface 20 j. Fluid emerging from thecapillary can then pass into stator through-hole 20 h and emerge atstator flat surface 24.

[0030] Referring again to FIG. 3B, the capillary tubes 13 emerge fromthe ferrule through-holes and extend up to the stator through-holes sothat the ends of the capillaries are, as noted above, substantiallyflush with the terminus of a tube pocket. The capillary ends disposed inthe tube pockets are naturally in the same relative positions in whichthe ferrules are arranged on the ferrule clusters. That is, thecapillary ends are distributed on the stator evenly around thecircumference of a circle having a single capillary end located at thecenter of the circle.

[0031] Referring once more to FIG. 1, the valve shown therein comprisesa rotor 26 which abuts the stator 20. The rotor may be of any number oftypes, two of which are shown in FIG. 6 and FIG. 7. Referring to FIG. 6,the rotor shown therein has a grooved stator contact surface 26 s and arotor shaft contact surface 26 t. A single groove 28 is cut into thestator contact surface 26 s. Referring to FIG. 7, an alternative rotor26A is shown with three grooves, exemplified by groove 29. The groovesdefine arcs lying along the circumference of a circle 26 j. As shown inFIG. 1, the stator contact surface 26 s abuts the stator flat surface24. Continuing to refer to FIG. 1, the rotor shaft contact surface isconnected to a rotor shaft 30 for varying the angle of the rotor withrespect to the stator. By rotating the rotor surface 26 s, the rotorgroove(s) may be selectively positioned to establish fluid communicationbetween specific pairs of capillaries 13. In the case of the rotor shownin FIG. 6, one end of the single groove 28 is always aligned with, andin fluid communication with, the center through-holes of the ferrulecluster back-up plate, ferrule clusters, and stator (12 g, 10 g, and 20g). As the rotor is rotated, fluid communication may be selectivelyestablished between the center capillary and any one the capillariesdisposed in ferrule through-holes 10 a through 10 f.

[0032] The rotor shown in FIG. 7 may be used when it is desired toestablish fluid communication between various pairs of the capillariesdisposed in ferrule through-holes 10 a through 10 f.

[0033] While the rotors shown in FIG. 6 and FIG. 7 use grooves cut intothe rotor surfaces to permit fluid communication between variouscapillaries, any type fluid communication channel could be provided onthe rotor. For example, rather than grooves, a channel could be cut inthe body of the rotor so that it has one opening at the center of therotor and another opening lying along the circle circumference 26 j.However, to minimize the dead volume of the valve, grooves cut into thesurface of the rotor are preferred as rotor fluid communicationchannels.

[0034] Returning to FIG. 1, rotor shaft 30 is connected to rotor surface26 t and is supported by bearing bushing 32, roller thrust bearing 34,and radial ball bearing 38. A set of Belleville springs 36 is used tobias the rotor shaft and rotor 26 toward the stator 20. A rotor driverpin 40 engages the rotor, and a handle 42 is used for operating therotor if manual rotation thereof is desired. Obviously, any number ofautomatic means for rotating the rotor could be connected to the rotorshaft.

[0035]FIG. 8 shows an alternative embodiment of the inventive valvewhich comprises three stacked ferrule clusters 44 and rotor mount 46 inplace of the rotor drive pin shown in FIG. 1. Also, the handle compriseshandle portion 46, threaded connection 48, and collar 50 attached torotor shaft 52. The valve in FIG. 8 is shown mounted to a mountingbracket 54. Also included in the valve of FIG. 8 is a Kel-F® (Kel-F is aregistered trademark assigned to Dyneon LLC) washer 19 disposed betweenthe ferrule compression plate 14 and base plate 16. The other parts areas shown in FIG. 1.

[0036]FIGS. 3A and 3B illustrate, as noted above, alternate methods ofconnecting the capillaries in the inventive valve. In Method A, shown inFIG. 3A, double-ended ferrules are used in a single cluster 15; inMethod B, which is used in the valve shown in FIG. 1, single-endedferrules are used in a double cluster. In both methods, each capillaryconnection is held in place by two ferrule gripping ends. Referring toFIG. 3A, when Method A is used the double-ended ferrules 15 a-15 g arearranged in the ferrule cluster 15 in a pattern similar to that shownfor the single-ended ferrules 10 a-10 g in FIG. 2. In FIG. 3A, onlydouble-ended ferrules 15 a, 15 g, and 15 d are shown in the sectionalview of the double-ended ferrule cluster 15. When method A is used, adifferent ferrule back-up plate 17 is utilized. Ferrule back-up plate 17is provided with conical impressions 17 a-17 g, of which only 17 a, 17g, and 17 d are visible in the sectional view. The conical impressionsin the ferrule back-up plate 17 correspond to double-ended ferrules 15a-15 g, and each receives one end of a double-ended ferrule in a fashionsimilar to the way in which stator conical impressions 20 a-20 g, fullyshown in FIG. 5, receive the opposite end of the double-ended ferrule.

[0037] Whether double-ended or single-ended ferrules are used, theindividual ferrules, including the single central ferrule if present,are preferably joined together as part of an integral, one-piece ferrulecluster. That is, the ferrule cluster is a one-piece cluster that is notadapted to be disassembled into multiple pieces. Such one-piece clusterscan be formed, for example, by compression molding of plastic materialsto form a plastic part, or by machining a piece of solid bar stock.Alternatively, an integral ferrule cluster as defined herein could beformed by fusing, gluing, soldering, welding, or using like operationsto join multiple pieces of material to form a single part. Referringagain to FIG. 2, in one embodiment of the invention, the ferruleclusters may be generally described as circular plates (although it neednot be circular) having individual ferrules integrally formed thereon.Naturally, non-integral ferrule clusters could also be used, such aswhen individual ferrules are belted, bolted, screwed, or wired togetherto form a cluster.

[0038] While the specific embodiments of the inventive valve shown inFIG. 1 through FIG. 8 utilize certain numbers of ferrules arranged inparticular ways in the cluster, the inventive valve and methodsdisclosed herein may generally employ any plurality of ferrules arrangedin any useful pattern in the ferrule cluster.

[0039] The ferrule clusters may be fabricated form any suitablematerial, including thermoset materials and thermoplastics.Polyether-ether ketone (PEEK) is a particularly suitable thermoplasticmaterial for fabricating the ferrule clusters of the invention. Therotor and stator of the inventive valve may be fabricated from anysuitable material, for example, metal, plastic materials, ceramicmaterials, or zirconia. In a preferred embodiment, the rotor and statorare ceramic or zirconia.

[0040] The valve of the instant invention may be fabricated to anyuseful size. However, the inventive valve is particularly useful inmicro applications, in particular those utilizing fluid flow rates of0.5 ml/min or less. Typically this includes capillary chromatography. Asused herein, and for the purpose of interpreting the claims of thispatent specification, the terms “capillary chromatographic system” and“capillary chromatography” shall be understood to refer to achromatograph, or chromatographic analyses performed thereon,respectively, which employ(s) one or more capillary columns. As usedherein, “capillary column” means a capillary (capillary tube) having alength greater than or equal to 25 meters, wherein the capillary has anoutside diameter from about 50 to about 1600 microns. It will beunderstood that the capillaries which may be connected to the inventivevalve need not be “capillary columns,” although they may be. Forexample, some of the capillaries may be shorter capillaries which areused to feed or transfer fluids to a capillary column. Those skilled inthe art will understand that the term “chromatographic analysis” refersnot only to the separation or partial separation of mixtures into theirindividual components, but also to methods in which a single, purematerial is analyzed. In the latter situation, it may technically be thecase that no “separation” occurs, because only a single, pure componentis present. Further, as noted above a distinction is sometimes madebetween chromatographic methods which are performed for analyticalpurposes and those which are performed for preparative purposes.However, for convenience, the term “chromatographic analysis” as usedherein will be understood to include separations and methods which areconducted for both analytical and preparative purposes.

[0041] Capillary chromatography has long been known for extremely highresolution, and it can be carried out using both gas and liquid mobilephases. In this sense the term “fluid” will be understood, as itnormally is,. to include both liquids and gases. The valve of thepresent invention is also useful in high pressure liquid chromatographic(HPLC) applications, including capillary HPLC. Thus, one embodiment ofthe invention is a capillary chromatographic system, including gaschromatographs and liquid chromatographs, comprising the valve of theinvention.

[0042] While the inventive valve and its components may be sized in anyuseful manner, certain valve and valve component dimensions arepreferred. Referring to FIG. 2 and FIG. 3A, the ferrule clusters of theinvention, both single-ended and double-ended, are also characterized bya height “h” and a ferrule cluster thickness “t.” In the case of thedouble-ended ferrules, “t” extends from one gripping end tip to theother, as shown in FIG. 3A. Preferably, the ferrule cluster height h isfrom 4 millimeters (mm) to about 8 mm, more preferably from about 5 mmto about 7 mm, and most preferably from about 5.5 mm to about 6.5 mm.Similarly, the ferrule cluster thickness t is preferably from about 2 mmto about 6 mm, more preferably from about 3 mm to about 5 mm, and mostpreferably from about 3.5 mm to about 4.5 mm. Referring again to FIG. 2,for both the single-ended and double-ended type of ferrule, thedimension d (gripping end tip diameter), is preferably from about 0.5 mmto about 1.00 mm, more preferably from about 0.75 mm to about 0.95 mm,and most preferably from about 0.85 mm to about 0.90 mm. The narrow endof the second through-hole conical section, d2, is preferably from about0.5 mm to about 0.8 mm, more preferably from about 0.55 mm to about 0.75mm, and most preferably from about 0.60 mm to about 0.70 mm.

[0043] In another embodiment of the invention, the capillaries 13 arefused silica capillaries having an outside diameter of about 365microns. In other embodiments, the outside diameter of the capillariesis between about 100 and 500 microns, and preferably between about 250and 400 microns.

[0044] In yet another embodiment, the present invention is a method forcarrying out a chromatographic analysis, comprising: a) providing aplurality of ferrules formed into one or more ferrule clusters, each ofsaid ferrules having a ferrule through-hole; b) placing a stator incontact with at least one of said ferrule clusters, said stator having astator front side and a stator flat surface opposite said front side,said stator front side having a plurality of impressions into which someor all of said ferrules are received, each of said impressions openingto a tube pocket, each of said impressions also having a statorthrough-hole opening onto said stator flat surface; c) disposing aplurality of capillary tubes through said ferrule through-holes and intosaid tube pockets; d) applying pressure to said one or more ferruleclusters; e) placing in contact with said stator a rotor comprising astator-contact surface and a fluid communication channel such that saidstator-contact surface abuts said stator flat surface and is rotatableabout an axis to establish fluid communication between selected pairs ofcapillaries through said fluid communication channel; f) placing one ormore of said capillaries in fluid communication with a capillary column;g) rotating said rotor to establish fluid communication between saidcapillary column and one or more of said capillaries; and h) passing afluid through one or more of said capillaries and into said capillarycolumn. In yet a further embodiment, the present invention is anautomated method or automated chromatographic system for carrying out achromatographic analysis using the valve of the invention.

[0045] In still another embodiment, the present invention is a methodfor connecting capillaries to a chromatographic system, the methodcomprising: a) providing a plurality of ferrules formed into one or moreferrule clusters, each of said ferrules having a ferrule through-hole;b) disposing a plurality of capillary tubes through said ferrulethrough-holes; c) providing a plurality of impressions into which saidsome or all of ferrules are received, each of said impressions having atube pocket into which one of said capillary tubes extends; and d)applying pressure to said one or more ferrule clusters.

[0046] While the present invention has been shown and described in itspreferred embodiment and in certain specific alternative embodiments,those skilled in the art will recognize from the foregoing discussionthat various changes, modifications, and variations may be made theretowithout departing from the spirit and scope of the invention as setforth in the claims. Hence, the embodiment and specific dimensions,materials and the like are merely illustrative and do not limit thescope of the invention or the claims herein.

I claim:
 1. A valve, comprising: a) a plurality of ferrules formed intoone or more ferrule clusters, each of said ferrules having a ferrulethrough-hole; b) a stator in contact with at least one of said ferruleclusters, said stator having a stator front side and a stator flatsurface opposite said front side, said stator front side having aplurality of impressions into which some or all of said ferrules arereceived, each of said impressions opening to a tube pocket, each ofsaid impressions also having a stator through-hole opening onto saidstator flat surface; c) a plurality of tubes, each of said tubesextending through at least one of said ferrule through-holes and into astator impression up to the terminus of said tube pocket; d) means forapplying pressure to said one or more ferrule clusters; and e) a rotorcomprising a stator-contact surface and a fluid communication channel,said stator-contact surface abutting said stator flat surface and beingrotatable about an axis to establish fluid communication betweenselected pairs of tubes through said fluid communication channel.
 2. Thevalve of claim 1 wherein said ferrule through-holes comprise first andsecond conical sections and a cylindrical section, said cylindricalsection having a diameter from about 0.38 mm to about 0.41 mm.
 3. Thevalve of claim 2 wherein said second conical section has a narrow enddiameter of from about 0.6 mm to about 0.7 mm.
 4. The valve of claim 3wherein each of said ferrules has a gripping end tip diameter of fromabout 0.85 to about 0.90 mm.
 5. The valve of claim 1 wherein said one ormore ferrule clusters comprise a plurality of ferrules distributed alongthe circumference of a circle and having a single ferrule positioned atthe center of said circle.
 6. The valve of claim 1 wherein said ferruleclusters are integrally formed.
 7. The valve of claim 1 wherein saidferrules have through-holes having a maximum diameter at any point alongthe through-hole of from 0.35 mm to 0.90 mm.
 8. The valve of claim 1wherein said valve comprises a single, double-ended ferrule cluster. 9.The valve of claim 1 wherein said valve comprises two or threesingle-ended ferrule clusters.
 10. The valve of claim 1 wherein saidfluid communication channel comprises a groove formed on said statorcontact surface.
 11. The valve of claim 1 wherein said one or moreferrule clusters have a ferrule cluster height of from about 5.5 mm toabout 6.5 mm.
 12. The valve of claim 1 wherein said one or more ferrulesclusters have a ferrule thickness of about 3.5 mm to about 4.5 mm. 13.The valve of claim 1 wherein said tubes are fused silica capillary tubeshaving an outside diameter between about 250 and 400 microns.
 14. Thevalve of claim 1 wherein said ferrules and said ferrule clusters arefabricated from polyether-ether ketone.
 15. The valve of claim 14wherein said stator and rotor are fabricated from zirconia or ceramic.16. The valve of claim 1 wherein said means for applying pressure tosaid one or more ferrules clusters comprises a compression plate and aferrule back-up plate, said compression plate being in contact with andurging said back-up plate against said one or more ferrule clusters inresponse to the tightening of a threaded connection.
 17. A capillarychromatographic system comprising a valve, said valve comprising: a) aplurality of ferrules formed into one or more ferrule clusters, each ofsaid ferrules having a ferrule through-hole; b) a stator in contact withat least one of said ferrule clusters, said stator having a stator frontside and a stator flat surface opposite said front side, said statorfront side having a plurality of impressions into which some or all ofsaid ferrules are received, each of said impressions opening to a tubepocket, each of said impressions also having a stator through-holeopening onto said stator flat surface; c) a plurality of capillarytubes, each of said capillary tubes extending through at least one ofsaid ferrule through-holes and into a stator impression up to theterminus of said tube pocket; d) means for applying pressure to said oneor more ferrule clusters; and e) a rotor comprising a stator-contactsurface and a fluid communication channel, said stator-contact surfaceabutting said stator flat surface and being rotatable about an axis toestablish fluid communication between selected pairs of capillary tubesthrough said fluid communication channel.
 18. A method for carrying outa chromatographic analysis, comprising: a) providing a plurality offerrules formed into one or more ferrule clusters, each of said ferruleshaving a ferrule through-hole; b) placing a stator in contact with atleast one of said ferrule clusters, said stator having a stator frontside and a stator flat surface opposite said front side, said statorfront side having a plurality of impressions into which some or all ofsaid ferrules are received, each of said impressions opening to a tubepocket, each of said impressions also having a stator through-holeopening onto said stator flat surface; c) disposing a plurality ofcapillary tubes through said ferrule through-holes and into said tubepockets; d) applying pressure to said one or more ferrule clusters; e)placing in contact with said stator a rotor comprising a stator-contactsurface and a fluid communication channel such that said stator-contactsurface abuts said stator flat surface and is rotatable about an axis toestablish fluid communication between selected pairs of capillariesthrough said fluid communication channel; f) placing one or more of saidcapillaries in fluid communication with a capillary column; g) rotatingsaid rotor to establish fluid communication between said capillarycolumn and one or more of said capillaries; and h) passing a fluidthrough one or more of said capillaries and into said capillary column.19. A method for connecting capillaries to a chromatographic system,comprising: a) providing a plurality of ferrules formed into one or moreferrule clusters, each of said ferrules having a ferrule through-hole;b) disposing a plurality of capillary tubes through said ferrulethrough-holes; c) providing a plurality of impressions into which someor all of said ferrules are received, each of said impressions having atube pocket into which one of said capillary tubes extends; and d)applying pressure to said one or more ferrule clusters.
 20. The methodof claim 19 wherein said ferrule clusters are integrally formed andcomprise a plurality of ferrules distributed along the circumference ofa circle having a single ferrule positioned at the center of saidcircle, each of said ferrule clusters having a height of from about 5.5mm to about 6.5 mm and a thickness of about 3.5 mm to about 4.5 mm, saidferrules having a gripping end tip diameter of from about 0.85 to about0.90 mm, said ferrule through-holes having a maximum diameter at anypoint along said through-hole of from about 0.35 mm to about 0.90 mm,each of said ferrule through-holes comprising a first conical section, asecond conical section, and a cylindrical section, said cylindricalsection having a diameter from about 0.38 mm to about 0.41 mm, saidsecond conical section having a narrow end diameter of from about 0.6 mmto about 0.7 mm.